气相色谱法测定制鞋业废气中正己烷含量

应用溶剂解吸-气相色谱法测定制鞋业排放废气中的正己烷,采用活性碳管采集成型车间排气筒中的废气,用二硫化碳解吸,填充柱分离,经FID检测器检测。废气中与正己烷共存的苯、甲苯、二甲苯在该方法下不干扰测定。解吸率高,测定精度高,该法具有准确、快速、灵敏、简便的特点。     

气相色谱法测定制鞋业废气中正已烷含量

应用溶剂解吸-气相色谱法测定制鞋业排放废气中的正已烷,采用活性管采集成型国间排气筒中的废气,用二硫化碳解吸,填充柱分离,经FID检测器检测.废气中与正已烷共存的苯、甲苯、二甲苯在该方法下不干扰测定.解吸率高,测定精度高,该法具有准确、快速、灵敏、简便的特点.     

顶空气相色谱法同时测定水中甲醇及苯

顶空气相色谱同时测定水中甲醇及苯含量,方法简单、快速,不需要专门的FFPA色谱柱.甲醇检出限0.01mg/mL,苯检出限0.01μg/mL.     

复合胺砜溶液同时吸收并分部解吸CO_2/SO_2/NO_x循环实验研究

在同一系统中联合脱除CO_2/SO_2/NO_x并实现溶液的解吸再生,不仅能够减少气体污染物的排放,而且具有系统简单、经济性高等优点。自行设计了同时吸收一分部解吸CO_2/SO_2/NO_x循环实验系统,以N一甲基二乙醇胺和二甲基亚砜配制成的复合胺砜溶液为吸收剂,在不同解吸温度和解吸气液比条件下,考察了富液中各组分的解吸情况,确定了CO_2和NO的最佳解吸条件。在整体循环实验中,考察了系统的可行性和稳定性,并考察不同浓度溶液的吸收、解吸特性。在整体循环实验中,实现了CO_2、SO_2、NO、NO_2的同时吸收和CO_2、NO的分部解吸,各组分的吸收速率逐渐减小,解吸速率逐渐增加,最终吸收一解吸达到平衡,平衡时吸收、解吸速率与吸收液浓度无关。     

超声浸提-No Gas-电感耦合等离子体质谱法测定工作场所空气中铊及其化合物

铊（Thallium,Tl）是一种有毒的金属元素,主要用于半导体、电子设备、农药和灭鼠剂的生产,会对职业人群的身体健康造成潜在的威胁,工作场所空气中铊及其化合物浓度的测定对保证职业人群的健康具有重要意义。虽然工作场所空气中痕量铊的毒性高于其他有毒金属元素,但对其研究却很少。目前工作场所空气中铊及其化合物浓度检测方法主要是原子吸收光谱法（AAS）,但该方法有不足之处。建立了超声浸提-No Gas-电感耦合等离子体质谱（ICP-MS）测定工作场所空气中铊及其化合物（以205Tl计）的新方法。在采样点,按照GBZ 159-2004方法用0.8 μm孔径的微孔滤膜对工作场所空气进行短时间采样。检测过程中,考察了不同超声浸提条件对测定结果的影响,并对质谱干扰及消除进行了分析。最终优化的实验条件为3%硝酸在室温条件下对采集的滤膜样品进行超声浸提10 min,采用No Gas模式对工作场所空气中铊及其化合物（以205Tl计）进行ICP-MS分析。在该实验条件下得出铊及其化合物在0.087～80 ng·mL-1浓度范围内呈现良好的线性关系（Y=0.009 2X-0.001 8,R=0.999 9）;检出限为0.026 ng·mL-1,当采样体积为75 L时,最低检出浓度为0.001 7 μg·m-3,最低定量浓度为0.005 7 μg·m-3。用质控样品（滤膜中铊质量控制样品ZK147和ZK148）验证了本方法的精密度和准确度,结果显示测定值与参考值之间无显著性差异,相对标准偏差（RSD）为0.77%和0.86%。用加标法（3倍于滤膜中铊含量的常见干扰元素）对建立的新方法进行干扰分析,回收率在97.2%～106.7%之间,表明本法抗干扰能力较强。用本法与国标方法《工作场所空气有毒物质测定 第25部分：铊及其化合物》（GBZ/T 300.25-2017）溶剂洗脱-石墨炉原子吸收光谱法相比较,10个实际样品的测定结果基本一致。相对于现行国标方法,该方法具有操作简单、检出限低、线性范围宽和准确度高的优点,能够满足实际工作场所空气中铊及其化合物的准确、快速、痕量及高通量测定需求。该方法有望成为工作场所空气中铊及其化合物测定的新方法,可更高效地为特定职业人群健康监护提供参考和依据。     

水样中总铬测定方法研究

用石墨炉-原子吸收光谱法(GF-AAS)和高锰酸钾-二苯碳酰二肼分光光度法,对环境水中的总铬进行了比较测定.结果表明:两种方法测定总铬的各项指标均在要求范围内,两种方法测定结果的RSD值均≤4.7%,加标回收率在94.5%-110%之间;表明两种方法均可测定水中总铬;但是石墨炉-原子吸收光谱法操作简便快速,更稳定.     

表面张力对PEO稀溶液粘度行为的影响

测定了不同分子量聚氧化乙烯 (PEO)在水和苯溶剂中的粘度 ,发现在低浓度区PEO水溶液的比浓粘度出现负偏离 ,PEO苯溶液比浓粘度与浓度之间依旧满足线性关系 .表面张力测定结果表明 ,PEO分子显著降低了水的表面张力 ,而苯的表面张力则不受影响 .PEO水溶液和纯溶剂水表面张力的不同干扰了高分子溶液和溶剂在粘度计中流过时间的测量 ,导致低浓度区PEO水溶液比浓粘度出现负偏离 .利用PEO水溶液和水表面张力测定结果 ,结合乌式粘度计的几何尺寸 ,定量分析了PEO水溶液和纯溶剂水表面张力的差异对粘度测量结果的影响 ,计算结果与实验结果基本相符 .如果用PEO水溶液流过时间对浓度作图的外推值t0 计算相对粘度 ,可以完全消除PEO水溶液和水表面张力差异对粘度测量的影响     

乙醇煤油混合燃料热解特性实验研究

本文实验研究了乙醇、煤油及其混合物的热解特性.利用气相色谱测量了其中氢气、甲烷、乙烯和一氧化碳的浓度.实验结果表明,燃料的热解率随温度的增加而增加.热解形成的气体中,乙醇热解得到的氢气浓度高于煤油,而甲烷和乙烯的浓度低于煤油.掺混乙醇后的煤油混合燃料热解时形成的氢气浓度随乙醇含量的增加而增加,对于在超燃冲压发动机中采用在煤油中添加一定量的含氧燃料(如乙醇、甲醇等)来解决着火和稳定燃烧问题具有很好的潜在优势.     

顶空气相色谱法测定聚苯乙烯日用品中苯乙烯单体的可溶出量和总量

应用自动顶空气相色谱法 ,分别以乙醇、乙醇 -水、水和二甲基甲酰胺 (DMF)作为提取溶剂 ,分析测定聚苯乙烯日用品中苯乙烯单体的可溶出量和总量 ,在优化的测定条件下 ,测量乙醇、乙醇 -水、水和二甲基甲酰胺标准溶液 ,检出限均 <0 .1mg/ L;回收率均在 89.6 %— 119%之间 ;其相对标准偏差 (RSD)分别为3.2 %、5 .9%、3.3%、3.4 %。     

Plot-U毛细管柱气相色谱测定工作场所空气中的甲醇

建立了用Plot-U毛细管柱气相色谱测定工作场所空气中甲醇的方法。硅胶管吸附空气中甲醇,水解吸后用Plot-U毛细管柱气相色谱(FID)测定。结果表明,甲醇浓度在0—200μg/mL范围内线性关系良好,线性方程为:y=1.2x-1.2(r=0.9998);检出限为1.4μg/mL,若采集1.5L空气样品,则最低检出浓度为0.9mg/m3;平均加标回收率在90.0%—91.0%之间;相对标准偏差在0.84%—2.60%之间。本方法适用于工作场所空气中甲醇浓度的测定。     

Trapping of V(benzene)2 sandwich clusters in a n-alkanethiol self-assembled monolayer matrix

V(benzene)₂ sandwich cluster cations produced in the gas phase were size-selectively deposited onto a self-assembled monolayer of n-hexadecanethiols (HDT-SAM) chemisorbed on a Au(111) surface as well as onto a bare Au(111) surface. The thermal chemistry of the neutralized clusters on each substrate was studied with temperature programmed desorption (TPD). From the analyses of the threshold in the TPD, the desorption activation energies of the clusters deposited were determined to be 64.4 ±12.8 kJ/mol for the Au(111) and 130 ±10 kJ/mol for the HDT-SAM. The remarkably large desorption activation energy from the SAM suggests that the deposited clusters are incorporated into the SAM matrix and firmly trapped inside the alkyl chains of the SAM.     

电子电气产品中挥发性有机化合物的释放量测定

采用小型释放舱-热脱附-气相色谱-质谱联用技术测定了电子电气产品中8种挥发性有机化合物（苯、甲苯、邻二甲苯、间二甲苯、对二甲苯、乙苯、乙酸丁酯和苯乙烯）的释放量.对一级脱附参数（一级脱附温度、一级脱附流量、一级脱附时间）、冷阱温度、捕集管脱附温度、脱附时间条件进行了优化,并进行了线性关系、回收率、精密度等试验.结果表明：本方法可用于测定电子电气产品中释放的8种常见的挥发性有机化合物的释放量,线性范围10-1000ng,当采样量为6L时,定量限为1.7μg/m3,回收率范围在89.5％-106％之间,相对标准偏差小于7％.     

基于微机电系统技术的高性能集成型微富集器

由于大部分环境样品的浓度非常低, 为了实现其直接检测, 提出将一种集成化的微型富集器应用到色谱系统中。富集器可实现色谱系统的进样与样品富集,能将色谱仪的检测限提高1~2个数量级。设计的富集器采用了高容量4平行通道结构,沟道内填充了高吸附率的Tenax-TA吸附材料,来实现对环境样品中挥发性有机化合物组分的富集。此外,为了密闭热解吸过程中所释放的组分,在微型富集器后集成了微型阀。试验结果表明,研制的微型富集器取得了15倍以上的富集因子。而且,通过微阀的控制,色谱峰的拖尾和峰展宽得到了有效的控制。因此,该微型富集器可广泛应用到环境样品的快速检测中,提高各检测器对复杂环境的适应能力。     

Catalytic reduction of NO in the presence of benzene on a Pt(3 3 2) surface

The catalytic reduction of NO in the presence of benzene on the surface of Pt(3 3 2) has been studied using Fourier transform infra red reflection-absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). IR spectra show that while the presence of benzene molecules at low coverage (e.g., following an exposure of just 0.25 L) promotes NO-Pt interaction, the adsorption of NO on Pt(3 3 2) at higher benzene coverages is suppressed. It is also shown that there are no strong interactions between the adsorbed NO molecules and the benzene itself or benzene-derived hydrocarbons, which can lead to the formation of intermediate species that are essential for N₂ production.TDS results show that the adsorbed benzene molecules undergo dehydrogenation accompanied by hydrogen desorption starting at 300 K and achieving a maximum at 394 K. Subsequent dehydrogenation of the benzene-derived hydrocarbons then begins with hydrogen desorption starting at 500 K. N₂ desorption from NO adlayers on clean Pt(3 3 2) surface becomes significant at temperatures higher than 400 K, giving rise to a peak at 465 K. This peak corresponds to N₂ desorption from NO dissociation on step sites. The presence of benzene promotes N₂ desorption, depending on the benzene coverage. When the benzene exposure is 0.25 L, the N₂ desorption peak at 459 K is dramatically increased. Increasing benzene coverage also results in the intensification of N₂ desorption at ∼410 K. At benzene exposures of 2.4 L, N₂ desorption develops as a broad peak with a maximum at ∼439 K.It is concluded that the catalytic reduction of NO by platinum in the presence of benzene proceeds by NO decomposition and subsequent oxygen removal at temperatures lower than 500 K, and NO dissociation is a rate-limiting step. The contribution of benzene to N₂ desorption is mainly attributed to providing a source of H, which quickly reacts with NO-derived atomic O, leaving the surface with more vacant sites for further NO dissociation.     

Adsorption and epitaxial growth of benzene on ZnO(1010) studied by thermal desorption spectroscopy,LEED and UPS

The adsorption and condensation of benzene on ZnO(101&#x0304;0) was investigated by thermal desorption spectroscopy and LEED. The first monolayer shows an ordered c(2 × 2) super-structure. First order desorption is observed. The desorption energy and frequency factor decrease from 73 to 56 kJ mole^?1 and from ~10¹⁵ to ~10¹² s^?1, respectively, with coverage increasing to 0.85. The second layer is more weakly bound. Two-dimensional (2D) island formation is deduced from peak shape analysis. Near completion, the second layer converts to a more tightly bound configuration as deduced from a sudden shift of the desorption peak and the formation of an additional c(4 × 3) LEED pattern. This pattern which can be identified as a property of bulk benzene is preserved upon epitaxial growth of the 3D benzene crystal. Angular resolved UPS measurements indicate the benzene molecules of the first layer to be arranged in an oblique position of low symmetry.     

Probing PAH formation chemical kinetics from benzene and toluene pyrolysis in a single-pulse shock tube

Benzene and toluene were pyrolyzed under highly argon-diluted conditions at a nominal pressure of 20 bar in a single-pulse shock tube coupled to gas chromatography/gas chromatography–mass spectrometry (GC/GC–MS) diagnostics. Concentration evolutions of polycyclic aromatic hydrocarbon (PAH) intermediates were measured in a temperature range of 1100–1800 K by analyzing the post-shock gas mixtures. Different PAH speciation behaviors, regarding types, concentrations and formation temperature windows, were observed in the two reaction systems. A kinetic model was proposed to predict and interpret the measurements. Through a combination of experimental and modeling efforts, PAH formation patterns from species pools of benzene and toluene pyrolysis were illustrated. In both cases, channels leading to PAHs basically originate from the respective fuel radicals, phenyl and benzyl. Due to the higher thermal stability of benzene, the production of phenyl, and thus most PAH species, occur in higher temperature windows, in comparison to the case of toluene. In benzene pyrolysis, benzyne participates in the formation of crucial PAH species such as naphthalene and acenaphthylene. Phenyl self-recombination takes considerable carbon flux into biphenyl, which serves as an important intermediate leading to acenaphthylene through hydrogen loss and ring closure. The resonantly-stabilized benzyl is abundant in toluene pyrolysis, and its decomposition further produces other resonantly-stabilized radicals such as fulvenallenyl and propargyl. Barrierless addition reactions among these radicals are found to be important sources of PAHs. Fuel-specific pathways have pronounced effects on PAH speciation behaviors, particularly at lower temperatures where fuel depletion is not completed within the reaction time of 4.0 ms. Contributions from the commonly existing Hydrogen-Abstraction-Carbon-Addition (HACA) routes increase with the temperature in both cases.     

气相色谱法同时测定乙酸乙酯、乙酸丁酯、环己酮和苯系物

采用活性碳吸附,二硫化碳解吸进样,利用DB-1毛细管色谱柱采用恒温条件分离,以FID为检测器,同时测定空气或废气中乙酸乙酯、乙酸丁酯、环己酮、苯系物。结果表明,该方法分离效果好,精密度高,准确度高,分析时间短,适合空气或废气环境分析的要求,结果令人满意。     

磁压缩系统中热脱附杂质粒子研究

磁压缩系统为俄罗斯实验物理研究院提出的核聚变方案。磁压缩系统腔室中杂质粒子可能来源于热脱附、等离子体刮削器壁等途径。利用ANSYS工具模拟5 MA脉冲电流流过腔室,并给出电极温度的二维分布图,结合研究小尺寸铜样品上杂质的解吸附来分析磁压缩系统腔室中热脱附过程产生的杂质粒子。通过测量3 keV的Ar+离子入射到Cu(110),Cu(111)样品表面的飞行时间谱,分析样品表面吸附的杂质种类,以及样品表面杂质含量随温度的变化关系。研究表明杂质粒子含量跟电极温度有关联性,且跟电极材料表面结构相关。